The 38 slides from Weiss's talk are here in
9 web pages. In the narrative below you can
click on any subject to go to its
page. Click here for a full
PDF version.

pg. 1 GR is one of
several possible covariant theories of gravity. It is only from
observation and experiment that we
conclude that GR is the valid theory. So, Weiss argues, we should base
the teaching of GR on experiment and
observation. To make his points, he uses the historically important
examples of gravitational red shift, bending of light, advance of
perihelion of Mercury, Shapiro test, and
Nordstrom's scalar theory of
gravity, which, though
Lorentz
covariant, fails to predict correctly the precession of perihelion
of Mercury or the gravitational redshift.

pg. 2 You
can motivate the need for curved space by imagining coordinates on a
rotating platform.
Basic phenomena, such as gravitational redshift, can be inferred from
the principle of equivalence.
The difficulty comes when you try to measure something: For the redshift
there are subtle
corrections to be determined and made.

pg. 4 Data from 9
solar eclipses show
how imprecise these measurements were. There are no error bars, but tiny
changes in the position or orientation of the plates or small shifts in
the telescope from thermal variations occurring as the Sun was eclipsed
would have produced large fractional errors in the results. There were
other difficulties
too.

pg. 7Shapiro time delay
provides a good context for teaching about coordinate freedom. To test
two different theories you must make complete consistent calculations
with each. Shapiro had to express the results in coordinate free form
(as invariants), and then compare. He found that Einstein's GR predicted
what was observed; Newton's theory did not.

[Cliff Will's book
Was Einstein
Right? gives a nice account of Shapiro's experiments that first
detected this effect. --editor]

pg. 8 Shortly after
publishing his GR theory, Einstein showed that there should be
gravitational radiation. To remind us that there are important
subtleties in this prediction Weiss points out two mistakes that
Einstein made in his first papers on gravity waves: 1) He
erroneously
predicted gravitational radiation from spherically symmetric motion,
which we now understand to be impossible; 2) He made a
factor of 2 error when
calculated the quadrupolar radiation that is the dominant form of
gravitational radiation.